Drive device having safety circuits using logic states for an elevator

Abstract

A drive device of an elevator includes a frequency converter to be connected to a public AC supply network and an elevator motor. The frequency converter includes a network rectifier configured to be connected to the AC supply network, a motor bridge to be connected to the elevator motor and a DC intermediate circuit located between the network rectifier and the motor bridge. The motor bridge is controlled by a control circuit which feeds the motor bridge with control pulses to regulate the motor speed. The drive device further includes at least one drive prevention circuit connected between the control circuit and the motor bridge. The drive prevention circuit is configured to obtain a safety signal from an elevator safety circuit includes two separate safety input circuits each configured to be connected to the elevator safety circuit to receive a safety signal. Each of the safety input circuits is configured to interrupt the connection between the control circuit and the motor bridge in response to the safety signal status.

The invention claimed is: 
     
       1. A drive device of an elevator, comprising:
 a frequency converter to be connected to a public AC supply network and an elevator motor, the frequency converter comprising:
 a network rectifier configured to be connected to the AC supply network; 
 a motor bridge to be connected to the elevator motor; and 
 a DC intermediate circuit located between the network rectifier and the motor bridge, 
 
 a control circuit which feeds the motor bridge with control pulses to regulate a motor speed; and 
 at least one drive prevention circuit connected between the control circuit and the motor bridge, the at least one drive prevention circuit being configured to obtain a safety signal from an elevator safety circuit, 
 wherein the at least one drive prevention circuit comprises two separate safety input circuits, each of the two safety input circuits being configured to be connected to the elevator safety circuit to receive a safety signal, 
 wherein the two safety input circuits are connected to a shut-down circuit of the at least one drive prevention circuit which is configured to monitor the safety input circuits, 
 wherein the shut-down circuit has a diagnosis circuit for the function of the safety input circuits, 
 wherein the diagnosis circuit interrupts the connection of the control circuit to the motor bridge in response to logic states of the two safety circuits differing from each other for at least a given period, and 
 wherein each of the two safety input circuits is configured to interrupt the connection between the control circuit and the motor bridge in response to a safety signal status. 
 
     
     
       2. The drive device according to  claim 1 , wherein the shut-down circuit of the at least one drive prevention circuit is configured to disconnect the connection between the control circuit and the motor bridge. 
     
     
       3. The drive device according to  claim 1 , wherein two separate signal communication channels are arranged between said elevator safety circuit and the two safety input circuits, whereby one channel of the two separate signal communication channels is connected to one of said safety input circuits, respectively. 
     
     
       4. The drive device according to  claim 1 , comprising a brake drive configured to be connected to at least one elevator motor brake, the brake drive being connected to a brake controller via a brake drop-out circuit,
 wherein the brake drop-out circuit has two brake safety input circuits configured to be connected to the elevator safety circuit, and 
 wherein each of the two brake safety input circuits is configured to interrupt the connection between the brake controller and the brake drive. 
 
     
     
       5. The drive device according to  claim 4 , wherein the two brake safety input circuits are connected to a shut-down circuit of the brake drop-out circuit, the shut-down circuit being configured to monitor the two brake safety input circuits. 
     
     
       6. The drive device according to  claim 5 , wherein the shut-down circuit is configured to monitor the two brake safety input circuits. 
     
     
       7. The drive device according to  claim 4 , comprising two solid state brake drives, the two solid state brake drives being each connected to a corresponding separate brake controller via a separate brake drop-out circuit. 
     
     
       8. The drive device according to  claim 1 , wherein safety signals are 24V DC signals. 
     
     
       9. The drive device according to  claim 4 , wherein at least one of the brake safety circuits is a digital isolator or optical isolator arranged in a control line of solid state switches of the motor bridge/brake drive. 
     
     
       10. The drive device according to  claim 1 , wherein the shut-down circuit comprises a fault memory. 
     
     
       11. The drive device according to  claim 10 , wherein the fault memory is configured to be connected to a reading device. 
     
     
       12. An elevator comprising:
 an elevator motor for moving an elevator car; 
 at least one elevator motor brake; 
 at least one drive device according to  claim 4 ; and 
 at least one elevator safety circuit having at least one safety signal output connected with each of the two brake safety input circuits. 
 
     
     
       13. The elevator according to  claim 12 , wherein the elevator safety circuit has two independent safety signal outputs which are connected via separate safety channels to one of the two safety input circuits of the at least one drive prevention circuit/brake drop-out circuit, respectively. 
     
     
       14. The drive device according to  claim 1 , wherein the two safety input circuits-are connected to a shut-down circuit of the at least one drive prevention circuit which is configured to monitor the safety input circuits and to disconnect the connection between the control circuit and the motor bridge. 
     
     
       15. The drive device according to  claim 5 , wherein the shut-down circuit is configured to monitor the safety input circuits and disconnect the brake drive from the at least one elevator motor brake dependent on output signals of both safety input circuits. 
     
     
       16. The drive device according to  claim 2 , wherein two separate signal communication channels are arranged between said elevator safety circuit and the two safety input circuits, whereby one channel is connected to one of said safety input circuits, respectively. 
     
     
       17. The drive device according to  claim 1 , comprising a brake drive configured to be connected to at least one elevator motor brake, the brake drive being connected to a brake controller via a brake drop-out circuit,
 wherein the brake drop-out circuit has two brake safety input circuits configured to be connected to the elevator safety circuit, and 
 wherein each of the brake safety input circuits is configured to interrupt the connection between the brake controller and the brake drive. 
 
     
     
       18. The drive device according to  claim 1 , wherein the shut-down circuit further comprises an interruption circuit which interrupts the connection between the control circuit and the motor bridge when signal outputs of the two safety input circuits are positive but an operation history of the two safety input circuits have ambiguity in a safety level.